Reliability of aluminum-nitride filled mold compound

Abstract

There are increasing demands placed on plastic packages to dissipate higher power levels and operate in high temperature conditions. Of concern is the reliability and the functionality of the IC device operating at higher power levels and/or high temperature conditions. One particular concern is the integrity of the aluminum-gold wire bond interface under high operating conditions. Mold compound stability is one of several factors contributing to the stability of the aluminum-gold bond. The Plastic Packaging Consortium (PPC), a Technology Reinvestment Project (TRP) funded by DARPA under SOL 94-27, addresses the needs to build-up and strengthen an onshore infrastructure for thermally-enhanced, ruggedized, and high density packages. An 160-lead (28/spl times/28/spl times/3.4 mm) plastic quad flat pack (PQFP) is used to characterize a thermally-enhanced and high operating temperature stable mold compound. The compound uses silica-coated aluminum nitride (AlN) filler to provide a thermal conductivity 4-6 X compared to fused silica-filled compounds. Thermal measurements show the AlN compound decreases /spl theta//sub JA/ by 8-10/spl deg/C/W compared to the fused silica-filled molded package. The thermal performance of the AlN-molded packages is equal to the embedded heat spreader enhancements. Use of alternate flame retardant synergists (antimony pentoxide-Sb/sub 2/O/sub 5/-or a new non-antimony type) provide a more stable compound as determined by High Temperature Storage Life (HTSL) testing at 200/spl deg/C. The testing confirms that the compounds formulated with the alternate flame retardant synergists (Sb3/sub O5/ or non-antimony type) improve HTSL performance.